Dry battery



Patented May 19, 1942 nity BATTERY vFrank MacCallum, Birmingham, England," assignor to Maxolite Holdings Limited, London,

England appiioatior october zo, 193s, serial No. 106,645 In Great Britain September 9, 1935 (ci. 13s- 131) Claims.

This invention relates to dry batteries and particularly concerns arrangements for distributing' the electrolyte in the cell or cells. It has been proposed to provide asupply of electrolyte for the cell or battery by`placing be tween the zinc electrode and the depolariser, a sheet of paper saturated with electrolyte.

One of the difficulties experienced, however,

has been that any lack of uniformity in the dis-Y tribution of the electrolyte has interfered with the efficient operation' of the cell and the'object of the present invention is to provide means for ensuring even distribution of the electrolyte.-

Referring to the drawings- Figure 1 is a sectional elevation of a battery incorporating the present i'nvention.

Figure 2 is a perspective view of a wafer or diaphragm according to this invention with one of the laminations partly removed.

Figure 3 shows in section a battery of the sack or dollie type, constructed according to the present invention.

Figure 4 shows part of saine removed from the zinc casing.

Figure 5 shows the zinc casing.

Figure 6 shows in section a slightly modiiiedv construction.

In Figure 1 of the accompanying drawings the .invention is applied to abatteryof the sandwich type including a plurality of zinc plates 5, eachv provided on one face with a carbon element or coating 6, these plates beingl arranged in spaced parallel relationship, with depolariser elements or tablets l larranged sandwichwise therebetween, and with lan electrolyte .wafer or diaphragm 8 between each depolariser tablet 'or element and the zinc face of the adjacent plate B.

Theend plate 9 has no carbon element or layer but an electrolyte wafer or diaphragm is. arranged between thefinner face of this plate and the adjacent depolariser tablet.

'Ihe assembly of cell elements is then coated with a laminated elastic skin I0, which completely encloses the battery and insulates and isolates the cells one from the other.

The skin l0 is shown as extending over the' The electrolyte wafer or diaphragm is formed .'frorn a plurality of piecesl of thin sheet material, each piece being coated with electrolyte and the coated sheets being superimposed and pressed or compacted together to form the laminated wafer or diaphragm shown in Figure 2.

The top sheet of the wafer is, for the purpose` of illustration, shown in Figure 2 partly peeled from the remainder of the wafer and it will be appreciated that in the final form all the pieces of the wafer lie closely one upon the -other with the electrolyte coating between each pair of adjacentpieces.

At Figure 3 is illustrated in section a sack or dollie type cell, constructed in accordance'with this invention.

The carbon rod I5 is surrounded by a depolariser I6 around `the exterior Aof which is wrapped'an electrolyte vwafer or diaphragm I1, constructed substantially as described above, this diaphragm being of somewhat greater length than the depolariser and being folded over the top of and beneath the depolariser, as shown in Figures 3 and 4.

The assembly of the form shown in Figure 4 is t inserted in a zinc casing I8 formed from a at` sheet or blank of zinc rolled up to form a cylindrical casing open at each end, the edges of the v sheet or blank overlapping slightly, as shown at 9.

A plug 20, which is conveniently formed from I* I rubber, is inserted into one openl end of the casE ing and the assembly -shovvrifinFigure 4j'lis thenl inserted through the other'OjLOpenendandnt v y The casing is vthen around the assembly tofp de agi d critic between the interior surfac of'fthe zinc'cas'ing t and the exterior surface of phragm I1.

If necessary, means such as a binding around the exterior of the zinc casing may be used to the.l 'electrolyteA die.:

i prevent the casing opening or moving awayfrom terminal strips la, but it win be understood that before using the battery the coating would be removed to expose the metalstrips.

'The elastic skin may be of the form set forth the exterior of the electrolyte diaphragm, and the whole battery is then coated with a laminated elastic skin 2l similar to the skin I0 of the f construction shown in Figure 1. This skin 2| completely encloses the cell and covers the Joints between the plug 20 and the zinc casing and extends across the open top o1' the casing so that the cell is insulated and when used with other or similarfcells there is complete isolation of cell from cell.

The coating 2| would. of course, be removed from the conducting cap-22er the carbon electrode and to form a battery from a plurality of cells arranged co-axially one upon'the other. A suitable conducting disc or piece may be provided beneath the base of the cell, this'disc or piece being connected to the zinc casing in a suitable manner to provideithe necessary electrical connection'. In the slight modification shown*y in Figure 6,'

the cell is constructed substantially described with reference to Figures 3 to 5, butthe carbofn electrode 23 is in the form of`a ilat lock or spade.. s

Figure 6 illustrates the preferred method of 'possible to avoid the disadvantages of all the sheets or pieces meeting on a common line without, however, overlapping .the tablet such as would form a double thickness of wafer along the joint. f p

The material must be sulciently thin so that when the wafer is completedit is conductive and does not undesirably increase the internal resistance of the cell. Another advantage of us-` ing pieces of thin material is that the thickness of the tablet and the size'of the completed battery are not undesirably increased.

In addition, the material is preferably sufciently tough even electrolyte to enable ft to withstand handling after the coating ofe'lectrolyte has been applied, the toughness also being desirable to ensure that the material will hold together when in use in the drybattery. if

It vhas been fund that paper of the kind known as manila paper is particularly suitable for the purposesince it is tough and suillcien'tly absorbent and will retain its toughness even when moistened with the coating of electrolyte.

The electrolyte coating penetrates the individual sheets and becomes evenly distributed over and through substantially the whole of the wafer I or diaphragm.

When moistened with the the particular circumstances under which it is required to work and the normal rated discharge of the battery in which the wafer is to be incorporated, but preferably not less than four pieces are used and any number up to ten or more pieces may beprovided, the number also depending upon the grade or thickness of paper used.

. With thin manila paper the thickness of which is of the order of 0.001 inch, it has been found lthat an average of six or seven superimposed pieces is suitablef for batteries having a light current output. For heavy duty batteries thicker paper may be used.

lThe thickness of the sheets, the number of sheets and the material of which they are made are interdependent to the extent that the sheets must 'provide a diaphragm which forms a housing for the electrolyte which will have a low resistance and which will permit the necessary mobility to the electrolyte and retain the electrolyte and not allow it to squeeze out at the edges to any serious extent.

The different sheets in the vsame Wafer need not all be of the same thickness or of the same material.

The electrolyte, which :nay be cf any suitable solution and prepared in' any known or convenient manner, is preferably applied in gelatinous form and may be applied to sheets cut to the required size and shape prior to the coating operation, or alternatively, may be applied to a continuous web or sheet which may subsequently be divided to form pieces of the desired size.

The electrolyte maybe applied by a brush or other mechanical means, or alternatively, the paper may be dipped in or passed through a bath of. electrolyte, the excess material being removed either mechanically or by gravity.

With a construction according to the present invention, the electrolyte is uniformly distributed,

since it 'is only necessary to provide a relatively thin coating on each sheet and in this manner it is easier to obtain a uniform coating than in cases where a thick layer of gelatinous electrolyte is applied to a single piece of paper. In this latter arrangement there is considerable danger of the electrolyte being displaced locally ory squeezed out from' one side during assembly of the battery so that in effect the layer of electrolyte is thinner at one side of the cell than at the other, causing a tendency for local action to be set up in a dangerous manner.

When a plurality of coated sheets according to this invention are superimposed it is diilicult, if not-impossible to squeeze the electrolyte from one side of the wafer, since the coating on each sheet is thin and, whilst it is possible to obtain any desired quantity of electrolyte by superimposing a suitable number of coated sheets, there is no free bulk of electrolyte which can readily bedisplaced or squeezed out of position since the layers of paper or othermaterial form a bond land hold the electrolyte in position. v

Thus, it is possible to obtain an electroly wafer or diaphragm of anydesired thickness and incorporating any desired quantity of electrolyte without introducing the possibility of lack of uniformity in the eelctrolyte distribution.

. With the construction according to the present invention, the internal resistance of the cell is low due to the uniform electrolyte distribution with a correspondingly good conductivity and eflicient life. y

In addition, the insoluble chlorides or salts formed during the process of discharge of the cell are distributed' in a uniform manner due to the uniform distribution of the electrolyte and the life vand efficiency of operation of the battery are correspondingly increased.

In addition, the life is lengthened and the eilciency of operation increased due to the even example, by coating one or more of the sheets with one electrolyte or chemical compound and one or more further sheets with another or different electrolyte or chemical Aso that when the sheets are superimposed to form the complete wafer, an eiiicient Vcombination of the two chemicals results. l

Forpexample, with an electrolyte including the chlorides of mercury, zincand ammonia, the mercury chloride may be provided on a sheet or piece of the wafer or diaphragm adapted to lie adjacent the zinc and the remaining chlorides applied to other sheets or pieces, the content of zinc chloride decreasing towards the side of the diaphragm adapted to lie nearest the carbon. electrede.

The grade or thickness of the sheets may be selected or varied to suit the particular require- :ments of the battery and two or more grades or thicknesses may be used in the construction of a wafer particularly when two or more electrolytes are incorporated.

The present invention provides an ideal electrolyte membrane which I have found to be entirely satisfactory in use and which is free from the defects Ihave encountered in connection with the methods used prior this invention.

I may apply the electrolyte to strips, rolls or large sheets of material and subsequently cutup such strips, rolls or sheetsto form the wafers or diaphragms of the desired size.

The invention is particularly applicable to dry batteries of the kind above described witnreference to the drawings, but may also be applied to inert cells or batteries may up in a dry condition and put in condition for .use when required, by adding water to the battery.

What I claim then is: v 1. An electrolyte wafer or diaphragm for a dry battery including a plurality of nat pieces of' pervious sheet material o! a thickness of the or- `solid form on each of said pieces, said layer being uniform both in thickness and consistency over the whole of the piece, said pieces being suflciently tough to withstand handling even when moistened with electrolyte and suiciently absorbent to hold the electrolyte. and the pieces being superimposed and compacted together. in nat form before assembly in the battery to construct a laminated flat wafer or diaphragm.

3. A dry battery including a carbonvelectrode,

a zinc electrode, a depolariser element betweenI said electrodes and an electrolyte wafer or diaphragm between said depolariser element and said zinc electrode, said wafer or diaphragm'including a plurality of at pieces of pervious sheet material of a thickness of the order of 0.001 of an inch, some of said pieces being coated with a uniform layer of Velectrolytein semi-solid form and the pieces being superimposed and compacted together in latv form before assembly in the battery to construct a preformed laminated at wafer or diaphragm with the electrolyte housed between the laminations of said lwaferor diaphragm.

4. A dry battery including a substantially at carbon electrode, a zinc electrode in the :form of a at plate, a depolarise'r tablet between .said

electrodes, and an electrolyte wafer or diaphragm between said depolariser element and said zinc electrode, said wafer or diaphragm including a plurality of fiat pieces of thin manila paper of a thickness of the order of 0.001 of an inch, some of said pieces having a thin uniform vcoating of electrolyte in semi-solid form, said pieces being sufllciently tough to withstand hantrolyte on each of said pieces, at least one of said pieces being coated with a layer of one electrolyte material in semi-solid form, at least one further piece being coated with a layerv of furtherelectrolyte vmaterial in semi-solid form', said l pieces being sufliciently tough to withstand handling even when moistened with electrolyte and sufficiently absorbent to hold the electrolyte, and the pieces being superimposed and compacted together in fiat form before assembly in the battery' so as to construct a preformed laminated ilat wafer or diaphragm in which is housed the e'ntire electrolyte supply for the battery.

FRANK MACCALLUM. 

